1-Hydroxy-3-alkyl-6,6-dimethyl-6,6a,7,8,10,10a-hexahydro-9H-dibenzo[b,d]pyr an-9-ones, their ethers and esters are disclosed in U.S. Pat. No. 3,507,885 as intermediates for the preparation of .DELTA..sup.8 or .DELTA..sup.9 -tetrahydrocannabinols (.DELTA..sup.8 or .DELTA..sup.9 -THC). No utility other than as intermediates was disclosed for these compounds until Archer, U.S. Pat. No. 3,928,598 issued Dec. 23, 1975, filed Nov. 5, 1973 disclosed their use as anti-anxiety and/or anti-depressant drugs and as sedative and/or analgesic drugs.
.DELTA..sup.9 -THC and other structurally related dibenzopyrans, either obtainable from natural sources or from various synthetic procedures, are known to be extremely insoluble in aqueous media. Consequently, there has been a continuing problem in determining the pharmacological activities of this type of compound when administered by the oral route since there exists a high degree of uncertainty as to the amount of absorption of these extremely insoluble substances after oral administration. The uncertainty as to the degree of absorption of these compounds is further complicated by a tendency of the compounds to exist in the solid state in several polymorphic forms.